1. Field of the Invention
The present invention relates to a piezoelectric thin film device including a single or a plurality of film bulk acoustic resonators (FBAR), and a method for manufacturing the piezoelectric thin film device.
2. Description of the Background Art
A piezoelectric thin device including a single or a plurality of film bulk acoustic resonators, such as a oscillator, a trap, a filter, a duplexer and a triplexer, has hitherto been manufactured by sequentially forming, on a supporting layer 92 formed on a base substrate 91, a lower electrode 93, a piezoelectric thin film 94, and an upper electrode 95 by sputtering or the like, and then forming a cavity C91 below a excitation region E91 of the piezoelectric thin film 94 by etching or the like (e.g. see Japanese Patent Application Laid-Open No. 2005-94735).
However, in the related art, it is difficult to obtain the piezoelectric thin film device with a desired characteristic since a piezoelectric material constructing the piezoelectric thin film 94 and a crystal orientation in the piezoelectric thin film 94 are limited to one which can be formed on the lower electrode 93. In particular, in the related art, it is difficult to construct the piezoelectric thin film 94 comprising a single-crystal piezoelectric material since the piezoelectric thin film 94 is formed on the lower electrode 93, which is a metal film.